1. Field of the Invention
The present invention relates to a hinge, and more particularity to a hinge of a portable computer that can position a monitor and a main frame when the monitor is pivotally opened to the main frame.
2. Description of Related Art
A portable computer is easy to carry and is available to any situation so that the portable computer is wildly used by many people. With reference to FIG. 8, the portable computer (70) comprises a main frame (72) with a pivotal end, a monitor (71) with a pivotal end and two hinges.
With further reference to FIG. 9, each hinge has a pivotal rod (50) and a sleeve (60). The sleeve (60) has a mounted end, a pivoting end and a receiving recess. The mounted end of the sleeve (60) is mounted in the pivotal end of the main frame (72). The receiving recess is formed in the pivoting end of the sleeve (60) and has a friction surface.
The pivotal rod (50) has a mounted end, an extending end (51) and an annular shoulder. The mounted end of the pivotal rod (50) is mounted in the pivotal end of the monitor (71). The extending end (51) of the pivotal rod (50) engages the receiving recess of the sleeve (60) so that the monitor (71) can rotate relative to the main frame (72). The extending end (51) of the pivotal rod (50) has at least one slot (52). The at least one slot (52) is formed longitudinally in the pivotal rod (50). The at least one slot (52) of the pivotal rod (50) can control tension of the pivotal rod (50) when the pivotal rod (50) engages the sleeve (60). The annular shoulder is formed between the mounted end and extending end (51) of the pivotal rod (50) and has a friction surface (53). The friction surface (53) of the pivotal rod (50) abuts against the friction surface (61) of the sleeve (60).
When the monitor (71) pivots to open relate to the main frame (72), two friction surfaces (53)(61) rub against to each other so that the monitor (71) can be held at a certain degree. However, the degree of opening of the monitor (71) depends on the friction between the friction surfaces (53)(61). After a period of use, the friction between the friction surfaces (53)(61) is getting lower so that the friction surfaces (53)(61) cannot hold the monitor (71) at the certain degree when the monitor (71) is opened.
To overcome the shortcomings, the present invention provides a hinge to obviate or mitigate the aforementioned problems.